Such energy supply devices can be used in automation systems to supply components close to the process and communication devices assigned to said components.
EP 1014531 A2 discloses such an energy supply device in which the functional units can be supplied from a high-frequency AC voltage which is individually output for each of the functional units via an inductor. As described the windings of the inductors are formed as substantially congruent conductor tracks of a multi-level printed circuit board which can be connected to one another, as can be known, in principle, from JP 62154609 A1. In addition, it is proposed to cause the inductance of the inductors by means of ferrite cores which project through openings in the multi-level printed circuit board. When designing the inductor with a ferrite core, additional measures should be taken to prevent the ferrite core from changing its position and/or breaking. An additional air gap or a change in the position of the core changes the inductance of the inductor and, as a result, can have an adverse effect on the explosion protection.
This known arrangement employs several disadvantages. For example, in order to accommodate the ferrite cores, recesses should be made in the multi-level printed circuit board. The production expenditure for the multi-level printed circuit board is very high as a result of the multiplicity of recesses and the fact that they can be each fitted with two ferrite core halves. In order to comply with the insulation distances specified according to the explosion protection standard, a minimum circuit board area and a plurality of metallization planes (layers) can be designed for the inductors. Furthermore, in order to achieve the specified inductance of the inductors, a multi-level printed circuit board having at least six metallization planes should be used, whereas four metallization planes suffice for the remaining wiring. Finally, the area of the inductors inside the multi-level printed circuit board limits the number of functional units which can be connected.